Digitalization of images has recently been remarkably developed, and digital broadcasting of satellite broadcasting, CATV and terrestrial broadcasting has been started in various countries. As the transmission scheme for the digital broadcasting, a scheme suitable for the characteristic of the used channel is selectively employed. For example, in the terrestrial broadcasting of U.S.A., a VSB (vestigial-sideband) modulation scheme is employed. Demodulation systems for digital modulated signals used in such broadcasting are described in various documents (see, for example, Non-patent Document 1).
In the case where a carrier is recovered from, for example, a VSB modulated signal including a pilot signal, the pilot signal is extracted, and a frequency error and a phase error are obtained on the basis of a difference between the extracted pilot signal and a reference signal.    Non-patent Document 1: Taga, Ishikawa and Komatsu, “A Study on QPSK demodulation system”, ITEJ Technical Report, published by the Institute of Television Engineers of Japan (ITEJ), August 1991, Vol. 15, No. 46, CE′ 91-42, pp. 20-24 (FIG. 30)